This invention relates generally to a device for reflecting light emitted by a lamp and more particularly to such a device for use with a compact fluorescent lamp.
Compact fluorescent lamps are widely used as an energy efficient substitute for conventional incandescent lamps. A four-tube compact fluorescent lamp, commonly referred to as a quad-lamp, is capable of producing with between 9 watts and 13 watts the equivalent lumens of an incandescent lamp of much higher wattage. In order to provide replacements for incandescent spot lights and flood lights, it is known to package a compact fluorescent lamp with its required magnetic ballast within a housing having a reflective surface and covered by a lens. One application for such replacement fluorescent lighting device is within a housing recessed within a ceiling.
The problem with such compact fluorescent lamps is that, in contrast to an incandescent lamp which produces light at, essentially, a point source, the fluorescent lamp is elongated along an axis and emits its light from coated surfaces in a direction perpendicular to this elongated axis. Because of the configuration of recessed lighting fixtures, the elongated axis of the fluorescent lamp tubes is aligned with the direction in which the light rays are to be directed. Therefore, essentially all of the light must be properly reflected by a reflector from an emitted direction, perpendicular to the axis of elongation of the tubes, to a direction aligned with the axis of elongation in order to be useful. Light that is not properly reflected into a beam is not useful light.
Replacement spot lights and flood lights utilizing compact fluorescent lamps have traditionally employed the same reflective surface design of incandescent flood lights and spot lights. Such design makes use of the focusing characteristics of a parabolic surface. However, because the characteristics of a fluorescent lamp are different from those of incandescent lamps, such parabolic reflectors are inadequate to meet the needs of compact fluorescent lighting devices as replacements for incandescent lamps.
Another restriction with recessed lighting is the length of the lamp. In order to replace a standard size incandescent lamp, the replacement compact fluorescent device must have a maximum overall length (MOL) that is within a given dimension. Because a longer reflector is capable of reflecting more of the light emitted by the lamp, the tendency has been to increase the length of the reflector in order to reflect more light. However, this restricts the applications to which the compact fluorescent lamp may be applied to those having liberal MOL requirements. Another solution has been to extend the diameter of the reflector in order to gather more useful light. However, just as replacement lighting devices have MOL requirements, there are also maximum diameter limitations. Therefore, there exists a need for improved reflector designs in order to make optimum use of the compact fluorescent lamp as a replacement for incandescent lights.